Out of the following, the strongest base in aqueous solution is

When we compare the basicity of the aliphatic amines, we would expect the basicity of tertiary amines to be the greatest, followed by secondary amine and then primary amine
But this is not so. The order of basicity is
NH₃ < primary amine ~ tertiary amine < secondary amine considering the steric hindrance and +I effect of methyl groups.